1. Field of the Invention
This invention relates generally to material or article handling and more particularly to article piling or arranging apparatus such as apparatus for stacking, aligning, and discharging folded corrugated paperboard blanks issuing from a folder-gluer machine.
2. Description of the Prior Art
Conventional folder-gluers are used to supply a stream of folded corrugated blanks in serial alignment with short spaces between the blanks. Examples of typical folder-gluers are shown in Spiess U.S. Pat. No. 2,637,251 and Lopez U.S. Pat. No. 3,266,391. The blanks issuing from the folder-gluer must be stacked in bundles, containing a preselected number of blanks, suitable for shipment to the user. It is usually necessary to square the blanks prior to bundling since they are not folded squarely in the folder.
The blanks are made from conventional corrugated paperboard consisting of four panels formed by slots and creases in the blanks. The blanks are folded about a center crease in the folder; glue is applied to an edge of one of the panels so that when the blank is folded, two of the panels overlap slightly and, when glued together, form a flat, tubular blank. The blanks are delivered flat to the user who opens and fills them with goods.
Since two of the panels are overlapped at the glue joint and the joint lies against another panel in the folded condition, it can be seen that three layers of material results whereas the remainder of the blank has only two thicknesses. This condition causes problems in stacking the blanks, particularly in automatic machines which have been developed for squaring and stacking the blanks. That is, stacks of such blanks tend to be unstable, particularly stacks of blanks of small sizes or unequal panel proportions.
Several automatic machines have been developed to square or align the folded blanks before or during the stacking operation. Generally, such machines square the blanks individually, it being understood that the glue joints are still tacky as the blanks are discharged from the folder-gluer. Examples of typical squaring and stacking machines are shown in Shields U.S. Pat. No. 2,988,236 and Lopez U.S. Pat. No. 3,122,242 and the aforementioned Spiess patent. Examples of improvements to such machines are shown in others of Shields' U.S. Pat. Nos. 2,931,520; 2,963,177; 3,409,148; 3,601,265; and 3,618,479.
Although considerable progress has been made in automatically squaring and stacking blanks for shipment, more exact alignment of the blanks is still sought along with greater accuracy in providing an exact preselected number of blanks in the final stacks.
Accordingly, a general object of the present invention is to improve the stacking and squaring of folded corrugated paperboard blanks and more particularly to overcome the disadvantages of existing machines to provide more exact alignment of the blanks and greater accuracy of the number of blanks desired in the final stacks.